Draftsman&#39;s instrument.



No. 652,832. Patented lulya, 1900 y L. M. cARM'lcAL. y

DRAFTSMANS INSTRUMENT.

(Application filed Nov. 11, 1899.)

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LUTHER M. CARMICAL, OF J ONESVILLE, VIRGINIA.

DRAFTSNIANS INSTRUNI ENT.

SPECIFICATION forming part of Letters Patent No. 652,832, dated July 3, 190.

Application tiled November 11,1899. Serial No. 736,640. (No model.) l'

To a/ZZ whom it may coce'rn:

Be it known that I, LUTHER M. CARMICAL, a citizen of the United States, and a resident of Jonesville,Lee county, State of Virginia, have invented certain new and useful Improvements in Draftsmens Instruments; and my preferred manner of carrying out the invention is set forth in the following full, clear, and exact description, terminating with claims particularly specifying the novelty.

This invention relatesy to measuring instruments,and more particularly to that class known as protractors57 and the object of the same is to produce an instru mentof this character having varied and Various capabilities.

To this end the invention consists in aprotractor constructed,.marked with scales, and used in any of the several ways hereinafter described .and as Vshown in the drawings, wherein, Y

Figure 1 is a plan view of my instrument in its preferred form. Figs. 2, 3, and 4c are views of the saine in somewhat-modified form. Figs. and 6 are elevations of the ears and other devices for supporting the shaft.

In the said drawings thenumeral 1 designates the body, which is shown in Fig. 1 as a rectangular frame, and 2 are extensionarms which may be hinged, as at 3, to lcertain extremities of thebody, so as to extend its dimensions when desired or to fold into small compass when not in use, and the outer edges of the body and arms are marked withordinary drafting-scales 4 for measuring pur poses. s

. 5 designates what I shall call the tangentarm, which in Fig. 1 forms'the upper side of the frame 1, while in Figs.' 2 and 3 its ex-v tremities are not extended into union with 8 and nearly intersects the outer edge ofthe tangentharrn 5, although the true arc isslightlyl broken, as indicated indottedjlines at 9. Ex'- cepting. theextension-arms, whose use isop? tional, thefeatures thus far described are common to all forms of my instrument 'savethat shown in Fig. 3.

The inner edge of the lower arm of the body is marked with a computing-scale 10, and a f similar scale l1 ismarked along .the outer edge of the tangent-arm 5, whereby the graduations of the two scales are opposite' each other. Both these scales start at 0 T at a vertical line intersecting the Fcenter 8 and the middle of the broken arc 9 and increase outwardly in both directions, as shown. The arc 7 of the protractor 6 is marked with a scale 12, whose grad nations radiate from the center 8 and may extend entirely across the protractor, if desired. The edge of the latter is cut out, as at 13, from about thegraduation v 10 on the protractor to about the gradu ation 26,? leaving a web 131 between the arm 5 and the protractor 6, so as to hold all parts rigidly in relative position, andthe scale 12 S continued along the protractor Where it is cut out, as shown. This cut-out is for the purpose of permitting the insertion of a pencil-point nearly up to the zero-line at the center of the broken are 9, and lthe fact that the are 7 is thus broken makes it possible to use f the computing-scale '11 yfrom its points 10 inward to zero for marking those points on the arc 7 which are hidden by the web 13. In Fig. 3 these cut-outs are omitted; butthe scale 12 is continued, as at 130, on at the inner edge ot' the protractor Gopposite the web 13, which supports the arm 5. In Fig. 2 the cut-outs are not so large, and hence the web 13 cannot be so wide. For measuring wide angles with the protractor shown in Fig. 1 this scale 12 is used as far as poss'ible, (here to thefpoint 85,) and then thel supplemental inside scale 14 is used up to ninety degrees.

cut it away, as at l5 in Fig. 1, in somecases I lill` said'cut-away portionv withanexten- 'sion'16, which is transparent or translucent land 'is graduated, as seen in Fig. 2, and this ,dispenses with thef necessity for thel inside scale 14.

- 2lrdesignates a point whichmayfbe 4 within the protractor (Sand .the operative edge of which is in yline withthe zero-marks o'f the two computing-scales 10 and 1l, while its other edge 22 is a matter of indiierence, and its extremity 23 stops short of the center 8. All parts thus far described are of the de- IOO sired size, shape, proportion, and material, though the instrument must be cheap and light without sacrificing strength and durability.

The particular utility of the device above described is as follows: The computing-scales on the frame an d4 extensionarm are obviously used for measuring purposes, being preferably in inches. The protractor is employed as usual for ascertaining angles from the center 8, and, as above explained, the breaking of the arc 7, as at 9, makes it possible to use the com putin g-scale'll of the tangent-arm for the smaller angles to a verticalavith almost the same precision as though the are were complete. y The cut-outs 13 permit the insertion of a pencil-point up to l0 on the protractor and -yet do not seriously weaken the web 1.31. Parallel lines are drawn alongy the outervor inner parallel edges of the frame, or afterdrawing one line the two zeros at 8 and f) are placed thereon, and lines parallel thereto can be indicated along the registeringscales 10 and l1 and the indication-marks afterward connected by lines parallel with that which passes through the zeros. In making these indicating-points if it should happen that the scale 10 must be used opposite 50 on the dotted line .fr of Fig. 1 the cut-away portion 15 permits the insertion ofthe pencilpoint', as will be clear. This dotted line oc occurs in Fig. 2 through the scale-numerals 40; but if it should here intersect 50 it can be seen through the transparent extension 16, as will beclear. Then the operator would place the lineuirst drawn on the two numerals. 50 and would indicate his parallelline opposite the two zeros and afterward draw it. Thus the same object is attained even though the eut-away portion l5 is filled by a transparent extension 16.: The point 20 may be used along its vertiealedge 21 in this last operation, or if it is desired to measure the area of a triangle its base may be laid along the line ot' the two zeros and the edge 21 after having first been measured by the scaleft and when the com puting-seale 10 intersects the apex of the triangle its altitude can be measured, as will be clear.

In FigAc, 30 is a shaft extending across the instrument and having rollers 3l at its eX- tremities. This and all that follows may be omitted, if desired. The end bars ofthe frame have u pturned ears 32, preferablystruck from the same material and provided with upright slots 33,in which the shaft 30 may work loosely, and 3st indicates L-shaped spring-catches carried by said ears with their bends extending across the slots in such manner as to hold the shaft at the lower end thereof with the rollers 31 resting on the table or paper and raise the instrument slightly above it or to permit the shaft to rise by the yielding of the spring into the upper end ot the slots, which will lift the rollers oit of the paper. As best seen in Fig. 5, the upper end of each ear is a member 35, pivoted at 36 at one end, its body extending across and closing the upper end of the'slot 33 and its other end latched, as at 37, whereby the slot may be opened when desired to entirely withdraw the shaft and rollers.

Fig. 6 is a detail of a slightlymodified form; Here the ear 32 has the same slot and spring; but there is a plate 40 sliding in gudesftl on the ear and having a stub-shaft 320 moving in'the' slot of the car. The plate is normally supported by a spring 42, and its upper end has a circular bearing 330 for the shaftfthe upper side ot' the bearing being yclosed byV a pivoted latch 35, constructed as slight distance from the paper and will perv mit its movement up and down over the same, so that parallelhorizontal lineslczjinl be .IOO

on a line parallel with its plane a'ndadapted l to extend from one side thereof, and graduation-,marks on all parts, substantially as described.

2. A draftsmans instrument consisting of a frame whose top and bottoni bars are parallel and inscribed with computing-scales both com meneing at zero and exte'ndingfutw'aid in both directions, all of theI graduations bel` ing opposite eachother; and'aprotracti` held rigidly between said bars with'the center of its are at one'of said zero-marks, the computing edge of the upper bar forming a small chord of said are which is thus broken at either side of its center, for use substantially as described.

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3. A draftsmans instrument consisting of a frame whose top and bottom bars are par'- allel and inscribed with computing-scales bothv commencing at zero and extending'outward in both directions, all of the graduations being opposite each other; and a protractor held rigidly between said bars with the center of its are at one of said zero-marks, the body of the protractor being integrally connected with the upper bar by a web and being cut out at either side of the same, as and for the purpose set forth.

4. A draftsmans instrulncnt consistingvof a frame whose top and bottom barsare 'par-` allel and inscribedwith computing-scales both commencing at Zero and extending outward in both directions, all of the graduations being opposite each other and a protractor held rigidly between said bars with the center of itsla'rc at one of said zero-marks, the computing edge of the upper bar forming a small chord of said arc which is thus broken at either side of its center, and the body of the protractor being united to said bar by a narrow web which is cut out at either side for the insertion of a pencil-point, substantially as described.

5. A draftsmans instrument consisting of a frame having parallel bars with correspondingly-disposed computing-scales each running from zero both Ways, and a protractor within said frame with the center of its arc op-A posite the zero on one bar and its body connected at its mid-length with the other bar, its ends being cut away, as and for the purpose set forth.

6. A draftsmans instrument consisting of a frame having parallel bars with correspondingly-disposed computing-scales each running from zero both ways, and a protractor within said frame with the center of its arc opposite the zero on one bar and its body connected at its mid-length with the other bar, its ends bein g cut away, and transparent graduated extensions filling the cut-away portions and uniting the ends of the protractor-body to the lower bar of the frame, as and for the purpose set forth.

7. A draftsmans instrument comprising a,

frame having two parallel bars with scales thereon, a protractor whose body is united at the center ofcits length to one bar and inscribed with graduations, and a point extending from said body inward toward the other bar with one straight edge at right angles to the length of the two bars, as and for the pur` pose set forth. g

S. A draftsmans instrument comprising a frame having two parallel bars with scales thereon, a protractor Whose body is united at the center of its length to one bar and inscribed with grad nations, and a point extending from said body inward toward the other bar with one straight edge at right angles to the length of the two bars, all said parts being integral and with the extremities of the protractor-body and the tip of the point slightly remote from the lower bar, as and for the purpose set forth.

9. A draftsmans instrument comprising a frame having scales marked thereon, ears rising from the frame, and bearings supported by the ears; combined with a shaft removably mounted in said bearings, rollers on the shaft standing beyond the end bars of the frame, and means for permitting a limited vertical movement of the shaft with respect to the frame whereby in one position the rollers are raised above the paper and in the other position of said shaft the frame is raised above the paper and the rollers rest thereon, as set forth.

10. A draftsmans instrument comprising a frame having scales marked thereon, ears rising from the frame, and bearings supported by the ears; combined with a shaft mounted in saidl bearings and carrying rollers, and spring-catches supported by the ears and adapted to retain the shaft and rollers in an elevated or depressed position with respect to the frame, as and for the purpose set forth.

11. A draftsmans instrument comprising a rectangular frame with scales marked thereon, ears rising from the end bars of the frame, and spring-catches on the ears; combined with plates moving in guides on said ears and engaged by said catches, springs normally supporting said plates, and rollers having their axes journaled in the plates, substantially as described.

12. A draftsmans instrument comprising a rectangular frame with scales marked thereon, ears rising from the end bars of the frame and vertically slotted, and spring-catches in the slots; combined with plates having stubshafts moving in the slots of the ears and engaged by said catches, bearings on the plates, and rollers having their axes journaled in said bearings, substantially as described.

13. A draftsmans instrument comprising a rectangular frame with scales marked thereon, ears rising from the end bars of the frame and vertically slotted, and spring-catches in the slots; combined with plates moving in guides on the ears, stub-shafts on the plates moving in said slots andl engaged by the catches, bearings in the upper ends of the plates, a shaft extending across the instrument and journaled in said bearings, and rollers on the extremities of the shaft, substantially as described. i

In testimony whereof l have hereunto subscribed my signature this the 9th day of November, 1899.

LUTHER M. CARMICAL.

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